Fork lift trucks typically have a mast. A carriage is attached to the mast. The material handling vehicle has powered means for elevating the carriage along the mast. In order to carry loads, a generally L-shaped fork is attached to the carriage. In many instances two such forks are attached to the carriage and loads are carried by inserting the forks into a pallet or other convenient device on which the goods to be handled are positioned. In other instances, the goods themselves can be directly contacted by one or more forks. When carrying articles which are relatively long and tubular such as rolled carpets a single fork may be used to carry the load.
With the variety of configuration and spacing of loads to be carried on fork lift trucks, it is common to provide a means for the adjustment of the location of the forks with respect to the carriage. If the desired load is to be picked up with two forks then the spacing between the forks may need to be adjusted to accommodate the particular pallet or other configuration of the load to be carried. Where a single fork is to be used such as in dealing with carpet rolls then one of the forks may be removed from the vehicle and the single fork would then typically be moved to the centre of the vehicle to evenly distribute the load on the vehicle wheels.
Typically the carriage which travels vertically up and down the mast comprises upper and lower mounting bars. When installing forks on a carriage having upper and lower mounting bars, the forks are normally provided with a pair of hook shaped hangers. The hangers extend toward the mast, that is, away from the load supported on the blade of the fork. The hanagers will usually extend vertically with the upper hanger extending downwardly over the upper mounting bar and the lower hanger extending upwardly over the lower mounting bar.
Typically, the upper mounting bar will be provided with a series of locating elements. These may be in the form of holes or slots in the upper mounting bar. Some type of interengaging structure such as a pin is provided to engage with the slots or holes in the upper mounting bar. Conventionally, the pin assemblies which engage with the holes in the upper mounting bar of the carriage, require additional parts to be welded to the hanger or make use of some type of relatively unsophisticated lever action which can be damaged in use.
It is apparent therefore that there is a need for a simplified device which provides positive locking action to maintain the fork in its desired lateral location. It is also desired that the device may work directly with the hanger rather than being separately formed and welded to the hanger.